Cellular communication networks evolve towards higher data rates, together with improved capacity and coverage. In the 3rd Generation Partnership Project (3GPP) standardization body, several technologies have been and are also currently being developed.
LTE is a recent standardised technology. It uses an access technology based on OFDM (Orthogonal Frequency Division Multiplexing) for the downlink (DL) and Single Carrier FDMA (SC-FDMA) for the uplink (UL). The resource allocation to wireless devices on both DL and UL is performed adaptively by the concept of fast scheduling, taking into account the instantaneous traffic pattern and radio propagation characteristics of each wireless device. Assigning resources in both DL and UL is performed in the scheduler situated in the radio base station.
In order to save power in wireless devices, DRX (Discontinuous Reception) can be used. A DRX cycle consists of a receiving period (also known as on duration) and an idle period (also known as off duration). No data can be received during the energy saving idle period, but only during the receiving period.
DRX is configured per wireless device and is governed by a set of power state parameters. However, it is not evident how to set the power state parameters. On the one hand, it is desired to save power by having long idle periods. But on the other hand, negative effects resulting from setting the wireless device in an inactive state, even temporarily, should be avoided if possible.
WO2010/044721 discloses methods and apparatus for controlling discontinuous receiver operation in a wireless communication device. In an exemplary embodiment, a wireless communication device configured to monitor a downlink signal during a series of regularly scheduled awake intervals and monitor the downlink signal for retransmissions during retransmission-monitoring intervals scheduled at a first predetermined delay from each detected data transmission to the receiver includes a control circuit configured to detect that a first retransmission-monitoring interval overlaps a previously scheduled radio activity during which the receiver is unavailable to monitor the first downlink signal, such as a measurement gap, and to adjust the first retransmission-monitoring interval, add an additional retransmission-monitoring interval, or both, responsive to said detecting. However, such a solution requires a successful detection of PDCCH transmissions to start additional retransmission-monitoring interval.
It would be greatly beneficial if discontinuous reception can be employed to reduce power requirements in the wireless device, but with reduced risk of any ill-effects due to the idle period.